Cold Start Emission Reduction via Coordinated Torque Control
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Solution Overview
Problem
Catalytic converters in internal combustion engines are less efficient at reducing emissions during cold starts due to their lower operating temperatures, requiring ignition timing retardation which compromises engine torque output.
Innovation Solution
A cold-start control system that includes a heat estimation module, torque request module, and propulsion torque determination module to estimate the heat required for the catalytic converter to reach light-off temperature, converting this heat into a torque request to maintain desired engine torque without compromising drive quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ignition timing is retarded to generate more heat to the exhaust gas, then catalytic converter temperature is increased, but engine torque output is reduced
Solution Approach 1:
The system performs preliminary heating of the exhaust gas during cold start conditions by retarding ignition timing before the catalytic converter reaches light-off temperature. This preliminary action ensures the catalytic converter is properly heated in advance, allowing it to function efficiently once operational, while the control system manages the torque impact through compensation strategies.
Solution Approach 2:
The system dynamically changes the ignition timing parameter based on exhaust temperature and catalytic converter state. During cold start, ignition timing is retarded to increase exhaust heat; as the catalytic converter approaches light-off temperature, the timing is adjusted back toward optimal values to restore torque output while maintaining emission control effectiveness.
2Object-generated harmful factors
If ignition timing is shifted from optimal point to heat exhaust gas, then emission reduction efficiency is improved, but drive quality is compromised
Solution Approach 1:
The control system continuously monitors exhaust temperature, catalytic converter state, and engine operating conditions to dynamically adjust ignition timing. This feedback mechanism ensures that ignition timing is retarded only to the extent necessary for heating the catalytic converter, and is adjusted back toward optimal values as conditions improve, thereby maintaining drive quality while achieving emission reduction.
Solution Approach 2:
The system transitions from static ignition timing to dynamic ignition timing control that adapts to changing engine and exhaust conditions. During cold start, the timing is dynamically adjusted to balance heating requirements with torque output, and continues to adapt as the system transitions to normal operating temperature, ensuring both emission control and acceptable drive quality throughout the transient process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively increases catalytic converter temperature while maintaining desired engine torque, ensuring efficient emission reduction during cold starts without noticeable step changes in torque delivery.
Implementation Method 1
Catalytic converters may be used to reduce emissions. Generally, the catalytic converters are more efficient at elevated temperatures.
Implementation Method 2
ignition timing may be retarded to generate more heat to the exhaust gas during the engine cold start period
Data Source
AI summary
A cold-start control system for an internal combustion engine includes a heat estimation module, a torque request module and a propulsion torque determination module. The heat estimation module determines an exhaust system temperature and estimates heat required to heat an exhaust system to a predetermined temperature. The torque request module generates a torque request based on the estimated heat. The propulsion torque determination module determines a desired engine torque based on the torque request.